548 Korean J Radiol 8(6), December 2007

Pelvic Hydatid Disease: CT and MRIFindings Causing Sciatica

Pelvic masses, especially hydatid disease, rarely present with sciatica (1, 2).We present the computed tomography (CT) and the magnetic resonance imaging(MRI) findings of a 49-year-old female patient with presacral hydatid disease,who was evaluated for her sciatica. We also want to emphasize the importance ofassessing the pelvis of patients with symptoms and clinical findings that areinconsistent and that cannot be satisfactorily explained by the spinal imaging find-ings.

isc herniation in the lumbar spine is a well-known etiology of back painsand sciatica, but whenever disc herniation of the lumbar spine is excludedby the employed imaging modalities, then the pelvis should be examined

for other possible etiologies of nerve compression. We describe here a patient, whowas complaining of sciatica, with no abnormal findings in her lumbar spinal magneticresonance imaging (MRI). The cause of her sciatica was found to be associated with apelvic hydatid cyst compressing the lumbosacral nerve plexus.

CASE REPORT

A 49-year-old female patient presented with a 2-year history of progressive rightlumbar pain radiating to her right lower extremity. The pain, which originated in theright buttock, extended down the posterior aspect of the right thigh and the calf to theankle. She was operated on for the right ovarian hydatid cyst 16 years before. Therewas no history of prior trauma.

On admission, the neurological examination revealed hypoesthesia, a slightweakness and atrophy of the abductor and extensor of the hip and the flexor musclesof the knee, and areflexia and radicular pain of the right leg. Treatment that includedanti-inflammatory drugs and exercise did not alleviate the pain. Therefore, a possibil-ity of lower lumbar disc herniation was considered. An MRI examination that wasintended to detect lumbar disc herniation was performed. The MRI of the lumbar spineshowed no nerve-root compromise, but on the very right parasagittal images, aglobular, septated cystic lesion in the right side of the pelvis was noticed (Fig. 1).

A review of the axial computed tomographic (CT) scan of the pelvis showed amultiloculated cystic mass located in the right presacral area (Fig. 2). According to thepelvic MRI, the multiloculated cystic lesion was located anterior to the right sacralforaminae. The lesion had low T1 and high T2 signal intensities, without contrastenhancement. Besides this right-sided cyst, there was another lesion with the sameimaging characteristics in the posterior left side of the rectum (Fig. 3A). The right-sidedlesion was in close proximity to the sacral nerve fibers. On the oblique coronal views,

Hatice Tuba Sanal, MDMurat Kocaoglu, MDNail Bulakbasi, PhDDuzgun Yildirim, MD

Index terms:Sciatica Pelvic hydatid cyst, Computed tomography (CT)Magnetic resonance (MR)

Korean J Radiol 2007;8:548-551Received July 21, 2006; accepted after revision September 28, 2006.

All authors: Gulhane Military MedicalSchool, Department of Radiology, 06018,Ankara, Turkey

Address reprint requests to:Hatice Tuba SANAL, MD, GulhaneMilitary Medical School, Department ofRadiology, Etlik, 06018,TR, Ankara,Turkey.Tel. +0090312 304 4701e-mail: tubasanal@yahoo.com

D

the displacement and compression of the lumbosacralnerve trunk could be well seen (Figs. 3B, C). There was noexpansion or destruction in the bony structure of theforaminae.

Because of the previous history of the right-sidedoophorectomy due to hydatid disease, the patient wasoperated on with the presumptive diagnosis of hydatiddisease. The diagnosis of a hydatid cyst was confirmedhistologically after surgical removal of the lesion. At thetime of the operation, the sacral nerve trunk was found tobe displaced and compressed by the right-sided presacralcyst. Mebendazole (100 mg twice daily for 4 months) wasprescribed.

DISCUSSION

Hydatid disease (echinococcosis), is a parasitic infectionthat’s caused by a cestode Echinococcus, mostly the formof E. granulosus (1). Hydatid cysts are noted throughoutthe world, but they are widespread in endemic regions.Echinococcal eggs of the adult worm are present in thesmall intestine of canine animals, and they are excretedwith the feces. When ingested by intermediate hosts likesheep, cattle or humans, these eggs hatch in the intestine ofthese intermediate hosts. Then the eggs, in the form ofoncospheres, penetrate through the mucosa of the intestineand diffuse into the blood and lymphatic circulation. Theyare transported by the circulation to the organs, mostly to

the liver and lungs, where they grow and produce cysts.Hydatid cysts are seldom primary in other organs, andthey are often part of generalized disease. Involvement ofthe pelvis in hydatid disease is reported to be 2% (25). In female, genital organs are reported to be the mostaffected areas in pelvis which can be attributed to theirrelatively ample bloodstream and true invasions fromconnective tissue of peritoneum of Douglas and suspensoryligaments (2, 6) Pelvic hydatid disease can be presentedwith vague abdominal pains due to irritation, swelling,menstrual irregularities, infertility and pressure symptomsinvolving the adjacent organs (bladder, ureters, rectum andvascular structures) (2, 4, 7 9). Symptoms indicative ofcompression of the lumbosacral plexus, as in our case, arereally quite infrequent, and on very few occasions theyhave been reported (4 6). In the case of Martin-Serradillaet al. (4), a pelvic hydatid cyst compressing thelumbosacral nerve plexus and the gluteal veins was shownby CT. Hassan et al. (5) documented a pelvic hydatid cystcausing erosion in the roof of the sacral foramina, extend-ing down to the coccygeal spine and causing swelling in thegluteal region, by CT.

The pelvic hydatid cyst in the case of Gupta et al. (6) waslocated in the right pelvis, and it extended through thegreater sciatic notch into the gluteal region.

The recurrence incidence of hydatid disease after surgeryis said to be 8 22% with recurrences most often notedwithin 2 years after the operation (2). Our patient was

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Korean J Radiol 8(6), December 2007 549

Fig. 2. A contrast enhanced CT scan of the pelvis in the axialplane showing the right-sided multiloculated cystic mass(arrowheads) in the presacral area in the close vicinity of thesacral foramen.

Fig. 1. T2 weighted, right parasagittal MRI of the lumbar spinereveals a multiloculated cystic mass in the presacral area(arrowheads).

operated on 16 years ago. This shows that the hydatid cystmay recur many years after the operation.

It is not infrequent to confront with sciatica in dailypractice of outcome patients in related departments.Lumbar disc herniation affecting the lower lumbar rootnerves is usually the reason of sciatica (5). Adnexial masseslike endometrioma, acetabular labral cysts, iliopsoas bursalcysts and pelvic hydatid cysts, as in our case, are other rarepathologies that may compress the lumbosacral plexus andcause sciatica (10 12).

In this patient, the hydatid cyst operation history was themain clue that helped make the correct diagnosis in a shorttime. Nevertheless, cyst formation may primarily takeplace in the pelvis, may be discovered incidentally, orcause irritation and compression symptoms and may causediagnostic dilemma (2).

This case demonstrates two important points. First,pelvic masses that include hydatid cysts may cause sciatica;

second, radiologist should be familiar with hydatid cystimaging features and direct the surgeon, so that carefulattempts be made during operation in order to preventrecurrences and choose the appropriate treatment options.

This parasite should be kept in mind and consideredwhen making the differential diagnosis of pelvic cysticmasses, in particularly if the patient is from an endemicarea. Along with their diverse symptomatology, pelvichydatid cysts may also cause sciatica.

In conclusion, if no pathology is evident for the lumbardiscal structures, in connection with the cause of sciaticaand lumbar back pains, then the pelvis should also beexamined for the possible etiologies of compression of thelumbosacral nerve plexus. Whenever a multiseptated cystis come across in a patient of an endemic origin with apositive history for hydatid disease like surgery, indicatingrecurrence, hydatid cyst is the most likely diagnosis.

Sanal et al.

550 Korean J Radiol 8(6), December 2007

A B

Fig. 3. A. An axial T1 weighted MRI of the pelvis showing the right-sided cyst(C) in the close vicinity of the sacral nerve fibers (arrowhead). Note the othercyst posterior to the rectum (arrow).B. In the oblique coronal T1 weighted image, the displacement and thecompression of the lumbosacral nerve trunk (arrowhead) by the cyst (C) canbe seen.C. The nerve plexus (arrowhead) compressed by the cyst (C) can be seen inthe oblique coronal T2 weighted image.

C

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